Use https://make.powerapps.com/
Make sure to select the correct environment.
The portal will show that the solution is installing or Installation is scheduled.
View the Solution list in Power Apps (refresh if needed) to see the progress of the installation. When the installation has finished, you'll see the Dual Write Core solution in the solution list.
Use the search field and search for Dual to find the solution if needed. When the Dual Write Core solution is found, the process is done.
The Azure Active Directory applications is accessed via the System Administration - Setup - Azure Active Directory applications (see screenshot below).
Set the User ID to the user in F&O that you want to handle the Integration (in this case we selected Admin)
User name will be the name that will be the owner of the records created in CE.
Prior to this step, a team should be created specificly for the integration. A new security role should also be created that has Read privilege with a User scope for each entity integrated through dual-write.
In test cases, the default team could be used and that team granted Admin rights. During implementation specific teams and privileges should be created.
Check the status of the installation via make.powerapps.com. Select solutions and make sure that the correct environment is selected.
This process can take from 30 minutes and up to an hour.
Search for Dual in the Search window and when the Dynamics 365 Finance and Operations Dual Write Entity Maps is in the list, the installation is done.